公路隧道围岩失稳概率计算中随机参数样本的修正

Amending of Random Parameters Sample in Failure Analysis of Tunnel Surrounding Rock

基于围岩变形破坏原理,建立了围岩稳定极限状态方程的普遍形式。研究了响应面方法求解该方程的过程,得出经典响应面方法仅仅适用于围岩物理力学参数随机分布曲线偏度系数为零的情况。针对围岩物理力学参数统计分布曲线的复杂性,利用统计矩参数对随机变量分布曲线形态特征的控制作用,提出了抽样样本修正方法和具体计算公式。归纳了修正后响应面算法的运行程序。以某公路隧道为例,分别采用经典算法和修正后算法计算了围岩稳定可靠度,然后与蒙特卡洛模拟结果进行了对照,经典方法计算结果与准精确解的绝对误差为1.017%,修正方法的计算结果与准精确解的相对误差为0.388%.

A general expression of limit state equation for surrounding rock stability was established based on its deformation failure principle.A procedure that the equation was solved through response surface method was researched and a conclusion that classical response surface method was only suitable for some physical and mechanical parameters which partial degree coefficient of distribution curve is zero was deduced.Aiming at a complexity of statistical distribution curve for surrounding rock physical and mechanical parameters,mended method and its calculation formula for samples was put forward by means of control role for statistical moment parameters to distribution curve configuration characteristic of random variable.An operation procedure of response surface method which basic random variable samples were mended was summarized.A stability reliability degree of surrounding rock for a highway tunnel was calculated by classical response method and mended response surface method respectively,then their calculation result was compared with Monte Carlo method.An Absolute error between calculation results of classical response surface method and Monte Carlo method is 1.017%,and Absolute error between calculation results of mended method and Monte Carlo method is 0.388%.